Brad Paisley and wife Kimberly Williams-Paisley (of 'Nashville') were recently swept up in a cruel hoax that all started with an email from a woman claiming her daughter was dying of neuroblastoma, a form of pediatric cancer.

"She said that her daughter had begged her to get in touch with me," Paisley's wife says during an upcoming episode of 'Nightline,' which airs Wednesday (Nov. 6).

The actress felt the email was genuine, since the mother expressed how she'd forgotten about the daughter's wish because of everything going on. "So it sounded very sort of real," she explains. "But she wasn't dying to get a hold of me. You know, that was kind of the beginning of the manipulation."

For 10 days, the pair spoke via emails, texts and through phone calls. Photographs of the little girl, allegedly named Claire, were sent along with journal entries and songs the girl had sung for Kimberly. At one point, Brad even got on the phone to sing 'Amazing Grace' for the sick child.

"You're singing to someone's dying kid," the CMA Awards co-host shares. "And in the middle of it, there's no way that's not real. How can that not be real?"

But then, red flags started to appear when Claire supposedly passed away. The Paisleys wanted to send flowers, but the little girl's mom wouldn't give out an address.

The red flags Kimberly saw were spot-on -- as it turns out, the photos were taken from the blog of a girl who actually has neuroblastoma. "That's the sickest part about this to me," Brad admits. "That is the part that when I start to talk about that, that's when I get really mad. That there were real kids, that there were real photos involved."

The Paisleys weren't the first to be "catfished" by elaborate hoaxes quite similar to this one. 'Nightline' investigated and found Little Big Town, Kate Gosselin, members of the Dallas Cowboy Cheerleaders and singers Mandisa, Natalie Grant, Francesca Battistelli and Carmen Hope Thomas were also scammed.

"I vowed then I was going to find her,” Brad insists of the scammer. “I’m going to find her, and I’m going to make sure this person isn’t able to do this, or isn’t capable of doing worse."

The 'Nightline' special airs Wednesday at 12:35AM ET, following the 2013 CMA Awards.